The present invention relates to a shock absorber control system, and more particularly to a shock absorber control system for controlling vehicle shock absorbers to allow a vehicle such as an automobile to turn around corners under stable conditions.
Known shock absorber control systems for use on vehicles control shock absorbers by adjusting their dampening forces in response to applied electric signals. When an angular velocity of rotation of a steering wheel or shaft exceeds a predetermined value, the shock absorber control system controls the shock absorbers to operated in a harder dampening mode. It is customary for the driver to move the steering wheel unintentionally slightly back and forth while the vehicle is running. This impairs the "feeling" the driver has while driving the vehicle since the shock absorbers are caused to switch between harder and softer dampening modes each time the steering angular velocity happens to exceed the predetermined value even upon such unintentional back-and-forth angular movement of the steering wheel.
One conventional shock absorber control system for adjusting shock absorber dampening forces in response to electric signals is disclosed in Japanese Laid-Open Utility Model Publication No. 56-147107 published on Apr. 8, 1980.
It is known that the angular velocity of a vehicle steering wheel as it is manipulated by the driver is liable to be lower when the steering wheel is turned than when it is returned. More specifically, when the vehicle enters a curved road, the steering wheel is turned by the driver at a relatively low angular velocity. However, when the vehicle runs out of the curved road, the steering wheel is returned at a relatively high speed since it is usually returned of its own accord.
The prior shock absorber control system utilizes only the angular velocity of the steering shaft as a parameter when the steering wheel is either turned or returned. Therefore, the shock absorbers remain in the harder dampening mode when the steering sheel is returned, though the softer dampening mode is preferable at that time for a better driver's feeling.